Apparatus for gear grinding



2 She.et-sSheet Zn varzTafx Aug. 19', 1930. "F. BURGESS APPARATUS FORGEAR, GRINDING Fi'led June 1 Aug. 19, 1930. F. BURGESS 1,773,386

APPARATUS FOR GEAR GRINDING Filed'Juhe 1925 2 Sheets-Shea 2 /76 were627/" /MAW Patented Aug. 19, 1930 PATENT- oFFIc-E FRANK nunenss, orwoLLAs'ron, MASSACHUSETTS APIARATUS IEOR. GEAR GRINDING Applicationfiled June 1,

This invention relates to apparatus for trueing hardened gears bygrinding them with the use ."of anemery or like hob device. The trueingand finishing of hardened gears by the use of a grinding hob of emery orthe like has-marked advantages in the way ofaccuracy and rapidity ofoperation, with continuous indexing, that are'well recognized in 'theart, butthe emery hob itself requires frequent dressing and attention tokeep the same trued up and in proper working condition, and has alsoinvolved large expense in the initial roughing out and trueing up of thesame from the emery blank of which it is composed. Such trueing up ofthe emery hob has ordinarily been accomplished by the use of diamondcutters which has involved great, and almost prohibitive expense for thediamonds which are rapidly used up in operating directly on an emeryhob, which it will be understood is usually of relatively substantialsize, e. g., about fourteen inches in diameter.

I have found that by employing an intermediate instrumentality, such asa formed disc of carborundum or the like for direct action upon thegrinding hob to dress and true the same, and by employing diamonds onlto dress and true the carborundum wheel, that the dressin r and trueingof the emery hob is made muc easier and quicker, and that a greateconomy is effected in the use of diamonds since there is only acomparatively small wear of the diamonds involved in keeping theintermediate carborundum wheel in proper operative condition. While Irefer herein to the intermediate wheel or disc as of carborundum. thisreference is to be understood as illustrative and not restrictive, andintended to include a wheel or disc made of any suitable substanceintermediate in hardness between the emery hob and the diamonds.

In accordance with my invention .1 provide in a single combined andorganized machine, in conjunction with the emery hob, work mounting andoperative connections, a mounting for a formed carborundum disc equippedwith operative connections including change gears for moving the samelater- 1925. Serial- No. 34,056.

ally in timed relation to a rotation of the emery hob so as to obtaina-correct lead of the carborundum disc causing it to follow the threadsof the emery hob; the machine or ganization also-including. a mountingfor. a trueing device holdin diamond points in position to' act uponthecarborundum disc when required. a

1 The foregoing and other objects and advantages of the invention willmore fully ap pear from the following detailed description taken inconnection with the accompanying drawings, and the distinctive featuresof novelty will. be pointed out in the appended claims. 1

- Referring to the drawings 2 Fig. l-is a front elevation of a machineembodying my invention with thediamo'nd trueing device removed;

Fig. 2 is a side elevation thereof with the. diamond trueing device inplace; and- Fig. 3 is a perspective view showingthe essential featuresofthe invention in a large- 1y diagrammatic form.

10 indicates the base and frame work of the machine having an uprightcolumn 11 at the back thereof in which is adjustably mounted a workarbor 12 on which a hard ened gear constituting the Work piece W ismounted. 13 indicates the emery hob which may be of relatively largedimension, e. g, about 14 inches in diameter. This emery hob is mountedon a shaft 14: .journaled on 'a carriage l5 fitted to slide on the base10. The shaft 14 isconnected through suitable shafting and change gears16 with the work in proper timed relation with the rotation of the hobfor continuous indexing. The driving impulse may be'imparted to theshaft 14 holding arbor 12 so that the work is rotated in anysuitablemanner as by a'belt connection 17 from a motor 18. 19 indicatesa disc wheel in a carriage 21 fitted to slide transversely of the base1O. The provision of this lateral slide carriage is to permit thecarborundum disc to be moved'transversely so as to follow precisely thelead of the spiral thread of the hob 13. To eifect such movement thecarriage 21 is engaged by a screw 22 whichis operated by a train ofchange gears from the shaft 14. It is desirable to provide a two speeddriving connection to the carborundum disc 19 so that it may be operatedat a relatively high speed for finishing and dressing the hob 13 toeffect such operation as rapidlyas possible, and at a relatively lowerspeed when the carborundum wheel is itself refinished and trued by thediamond trueing device as presently described. As I accomplished thistwo speed drive of the shaft 20 by a belt connection 24 which engagesstepped pulleys 25, 26

on the shaft 20 and a driving countershaft 27 respectively. When thegrinding hob is to be acted on by the carborundum disc to finish anddress the same, it is turned slowly, preferably'by a hand operatedconnection, though it might be turned by power. For turning the hob byhand I show a worm wheel and worm connection 28 therefrom leadingthrough a shaft 29 'and bevel gears 30 to a hand crank 31. The turningof this. crank thus rotates the grinding hob slowly, while through thedescribed change gears 23 and screw 22 the carborundum disc 19 is at thesame time moved slowly laterally so-..as to follow the lead of thespiral groove of the hob. For trueing the carborundum disc 19 I providediamond points There are preferably two of these points to engagesimultaneously opposite sides of the carborundum disc periphery. Thesediamond points may be borne by any suitable holder capable of presentingthem properly to the carborundum disc surface, but preferably, and asherein illustratively shown, I mount them upon the inner ends of arms 33which are pivoted together at 34 as a tongs construction with theirouter end portions engaged by a tension spring 35 to hold them engagedwith a template form 36-which thus determines the shape imparted to theperipheral side portions of the carborundum disc in accordancemeansconstituting no part of t e present invention.

Having described my invention, what I .claim as new and desire to secureby Letters Patent is:

1. The hereindescribed method of finishing and preserving the accuracyin use of grinding elements for truing gears, which consist such elementby means of a disc adapted to be moved in one direction into contacttherewith and having a formed periphery of relatively harder material,and in truing and preserving the accuracy of such finishing disc by theuse of still harder members controlled harder substance, and in movingsaid disk free from contact with said hob and then truing and preservingthe acchracy ofsuch finishing disc by the use of a diamond controlled bya template form. 1

3. The combination with apparatus for grinding gears and thelike,equipped with a grinding hob, of a disc having a eriphery of relativelyharder material than t e grinding) hob, formed to finish the grooves ofsuch ho a truing device bearing diamond points and .having a templatecontroller, a slidable support for said disc, and means for moving saidsupport to position said disc in contact with said hob or in positionfor said diamond points to true said disc.

4. The combination with mechanism for grinding gears equipped with anemery hob, of a disc for finishing the spiral tooth rib of suchhobmounted to be engaged therewith at will, and having connections with thehob to be moved laterally so as to follow the spiral tooth curvethereon, a diamond truing device for truing said disk, a slidablesupport for-- said finishing disk and means for moving said support tobring said disc in coacting relation with either the truing device orsaid hob.

5. The combination with a grinding hob equipped for operation to true agear or the like, of a finishing-disc of carborundum, having itsperiphery formed to furnish the spiral tooth curve of such hob, meansfor moving such disc laterally at a rate to cause it to follow thespiral tooth of the hob, a diamond truing device having a templatecontrol for truing such finishing disc, and means for operating saidfinishing disc at a relatively high speed when operating on the grindinghob, or

at'a relativelylow speed when engaged by the diamond truing device atwill.

6. The combination with a hob for grind:

ing. gears, a finishing disc of carborundum,

having its periphery. formed to finish the spiral tooth curve of saidhob, means for moving the disc laterally at a rate to cause it to followthe spiraltooth of the hob, a

diamond truing device for truing said disc provided with atemplate'control, a slidable support for said disc, means for movingsaid support to bring said disc into coacting relation with either saidhob or said. truing device, and means for rotating said finishing discat a relatively high speed when operating on said hob or at-a relativelylow speed when engaged by the truing device.

7. The combination with a hob for grinding gears, a finishing disc ofcarborundum, having its periphery formedto finish the spiral tooth curveof said hob, means for moving the disc laterally at a rate to cause it.to follow the spiral tooth of the hob, a diamond truing device fortruing said disc provided with a template control, a slidable supportfor said disc, means for moving said support to bring said disc intocoacting relation with either said hob or said truing device, means forrotating said finishing disc at a relatively high speed when operatingon said ho'o 01' at a relatively low speed when engaged by the truingdevice, and means for rotating the grindinghob slowly when I said discis coacting with said hob.

8. The combination with a hob for grinding gears, a finishing disc ofcarborundum,

having its periphery formed to finish the spiraltooth curve ofsaid hob,means for moving the disc laterally at a rate to cause it to follow thespiral tooth of the hob, a diamond truing device for truing said discprovided with a template control, a slidable support for said disc,means for moving said support to bring said disc into cqact-' ingrelation with either said hob or said truing device, means for operatingsaid finishing disc at a relatively high speed when operating on saidhob or at a relatively low speed when engaged by the truing device; andmeans for manually rotating the grinding hob slowly when said disc' iscoacting with said hob.

9. The combination with a hob for grinding gears, a finishing disc ofcarborundum,

having its periphery formed to finish the spiral tooth curve of saidhob, means for moving the disc laterally at a rate to cause it tofollowthe spiral tooth of the hob, a

. diamond truing device for truing said disc provided with a templatecontrol, a slidable support for said disc, means for moving said supportto bring said disc into coacting relation with either said hob or saidtruing device, means for operating said finishing disc at a relativelyhigh speed when operating on said hob or at a relatively low speed whenengaged by the truing device; means for rotating the grinding hob slowlywhen said disc is coacting with said hob; and means for rotating saidhob rapidly when said disc is disconnected therefrom and operating totrue a gear.

10. The combination with a hob for grinding gears, a finishing disc ofcarborundum,

having its periphery formed to finish the spiral tooth curve of saidhob, means for moving the disc laterally at a rate to cause it to followthe spiral tooth of the hob, a diamond-truing device for truing saiddisc provided with atemplate control, a slidable support for said disc,means for movingsaid support to bring said disc into coactingrelatatable shaft, and connections between said rotatable shaft and workarbor whereby said work arbor will be rotated in timed relation to therotation of said hob.

Intestimony whereof, I have signed my name to this specification.

FRANK BURGESS.

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